Means for controlling alternating currents



E. F. w. ALEXANDERSON.

MEANS FOR CONTROLLING ALTERNATING CURRENTS.

APPLICATION FILED APR. 11. 1918.

Patented Mar. 16, 1920.

IIIIMIHII Inventor: Ernst F. \Mfflexanderson,

His fittovneg.

UNITED STATES. PATEN T OFFIQE.

ERNST F. W. ALEXANDERSON, OF SGI-IENECTADY, NEW YORK, ASSIGNOR TOGENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MEANS FOR CONTROLLING AIiTERNATING CURREN TS.

Specification of Letters Patent.

Application filed April 11, 1918. Serial No. 227,946.

for Controlling Alternating Currents, of.

which the following is a specification.

My present invention relates to electromagnetic apparatus for usewithhigh frequency alternating currents, either for controlling the flowof such currents in a circuit. for multiplying the frequency thereof, orfor similar purposes. More particularly my invention relates toelectromagnetic apparatus of a kind which I term magnetic amplifierssuch, for example, as are described in my prior patent $51,206,643.

The object of my invention is to improve. the construction of magneticamplifiers of the class described in my prior patent in order to renderthem more efficient for the purpose for which they may be employed. Inthe construction of these devices it is desirable that the magneticcircuits and the windings be so arranged that no high frequency currentwill flow in the circuit which supplies the controlling current. Whereseparate windings are employed for the high frequency current and thecontrolling current, this result may be accomplished in eitherof twogeneral ways: F irst. the con trolling winding may be made inductivelyindependent of the high frequency winding: second. the windings mav beso arranged that one-half of the controlling winding is interlinked withthe high frequency flux in one direction and the other half isinterlinked with the high frequency flux in the opposite direction sothat the induced potentials are neutralized in the winding itself. In mypresent invention the desired result is accomplished in the first waymentioned.

The features of my invention which I consider novel are pointed out withparticularity in the appended claims. The-invention itself. however.together with further objects and advantages, will best be under stoodby reference to the following description taken in connection with theaccompanyingdrawing in which Figure 1 shows a plan View of one of myimproved devices wvith certain portions broken away, and Fig. 2 shows anelevation.

As indicated in the drawing, the magnetic core is built up of a largenumber of thin laminations of magnetic material separated by sheets ofinsulating material. The top layer as shown in Fig. 1 consists of twosheets 1 and 2 of magnetic material of Patented Mar. 16, 1920..

trapezoidal shape with the tops of the trapczoids adjacent each otherbut separated by an air gap 3. Thislayer is separated from the nextlayer by sheets of insulating material 4, 5, of slightly larger areathan the sheets 1 and 2 so that the edges of these sheets project beyondthose of the sheets 1 and 2. The second layer is made up of two similarsheets 6, 7 of magnetic material of the same shape and size as thesheets 1 and 2 but placed at right angles to the sheets 1 and 2. Thesecond layer is separated from the third layer by the sheets 8 and 9 ofinsulating material which are arranged relatively to the sheets 7 and 8in'the same manner that the sheets 4; and 5 are arranged rela tively tosheets 1 and 2. The third layer is made up and arranged in the samemanner as-the first layer and the fourth layer in the same manner as thesecond layer. The laminations are built up in this way until the desiredthickness of the magnetic structure is obtained. I find that it isimportant that the sheets of insulating material shall be larger thanthe sheets of magnetic ma- 7 placed in the openingslO, 11, 12, 13 and14, as indicated. These windings are so arranged that the high frequencyflux will circulate through the core around the opening 10. The coils19. 20, 21 and 22 which carry the controlling current are also locatedin the openings 11, 12-, l3and 14,

as indicated. The magnetic circuits for the controlling flux arecompleted by meansof U-shaped sheets 23, 2t, 25 and 26 which areinserted between the trapezoidal-shaped sheets as indicated. TheseU-shaped sheets form yokes which may be removed and thus allow the coilscarrying the controlling current to be removed independently of the highfrequency coils. It will be apparent that each of the controlling coils19, 20, 21 and 22 will produce a flux in two complete magnetic circuits.For example, the coil 21 will produce a flux through the U- shapedsheets 23 and the portion of the core embraced by the high frequencycoil 18.

It will also produce a flux through the- U-shaped sheets 26 and theportion of the core embracedby the high frequency coil 17 Thus thecontrolling flux will be effective in the part of the magnetic structurewhich is traversed by the high frequency flux but none of the highfrequency flux will pass through the U-shaped sheets and no highfrequency currents will be induced in the. controllingwindings. In otherwords, the controlling windings are in noninductive relation to the highfrequency windings and each of the magnetic circuits for the controllingflux are partly coincident with and partly separate from the anagneticcircuit for the high frequency ux. I

It will be noted that the high frequency magnetic circuit comprises fourportions at the air gaps 3 which are of much smaller cross section thanthe other portions. This feature is of advantage in a device of the typehere involved as the portions of smaller cross section determine thesaturation of the core and the portions of larger cross section tend toreduce the magnetizing current when the core is not saturated, thusartificially increasing the range of permeability of the combinedstructure. Each of the magnetic circuits for the controlling fluxesincludes one of these portions of the magnetic circuit for the highfrequency flux of relatively small cross section.

When a sufficient number of laminations are piled on top of one anotherthe mass is secured by means of the clamping plates 27 and 28 which areheld together by means of bolts 29.

The magnetic material used should be of such a nature and in such thinsheets that its permeability is substantially independent of thefrequency of the magnetizing current at the radio frequency at which itis operated. I have found in practice that the sheets should preferablybe two mils or less in thickness.

While I have illustrated and described a tions may be made in single Wayof carrying my invention into effect, it is apparent that manymod1ficathe structural details Without departing from the scope-of theappended claims.

- What I claim as new and desire to secure by Letters Patent of theUnited States, 1s, 1. Means for controlling the flow of radio frequencycurrent comprising a magnetic core made up of a plurality of thin sheetsof magnetic material separated by sheets of insulating material, thearea of the sheets of insulating material being greater than the area ofthe sheets of magnetic material so that their edges project beyondthoseof the sheets of magnetic material, the sheets of magnetic materialbeing so arranged that certain portions of the core have a much smallercross sectional area than other portions and the magnetic material beingof such a nature and in suchthin sheets that its permeability issubstantially independent of the frequency of the magnetizing current atordinary radio frequencies.

2. An apparatus of the class described comprising a magnetic core madeup of a plurality of-thin sheets of magnetic material separated bysheets of insulatingmaterial, the area of the sheets of-insulatingmaterial being greater than the area of the sheets of magnetic materialso that their edges pro- ]ect beyond those of the sheets of magneticmaterial and the magnetic material being of such a nature and in suchthin sheetsthat its permeability is substantially independent of thefrequency of the magnetizing current at ordinary radio frequencies.

3. An apparatus of the class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material, each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezoidal shape with thetops of said trapezoids adjacent each other but separated by an air gap,the sheets of every alternate layer being arranged at a right angle tothe sheets of every other layer and registering notches in the top ofeach trapezoidal sheet whereby a central opening is formed in the core.

4. An apparatus of the 'class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material. each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezbidal shape With thetops of said trapezoids adjacent each other but separated by an air gap.whereby notches are formed between the adjacent non-parallel sides ofthe trapezoidal sheets of each layer. the sheets of every alternatelayer being arranged at a right angle to the sheets of the 4 Lesaaaeother layers and registering notches in the top of each trapezoidalsheet whereby a central opening is formed in the core.

5. An apparatus of the class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material, each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezoidal shape with thetops of said trapezoids adjacent each other, whereby notches are formedbetween the adjacent v non-parallel sides of the trapezoidal sheets ofeach layer, the sheets of every alternate layer being arranged at aright angle to the sheets of every other layer, registering notches inthe top of each trapezoidal sheet whereby a central opening is formed inthe core, and coils adapted to carry high frequency current located insaid central opening and-said notches so as to inclose portions of themagnetic core.

6. An apparatus of the class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material, each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezoidal shape with thetops of'said trapezoids adjacent each other, whereby notches are formedbetween the adjacent non-parallel sides of the trapezoidal sheets ofeach layer, the sheets of every alternate layer being arranged at aright angle to the sheets of every other layer, registering notches inthe top of each trapezoidal sheet whereby a central opening is formed inthe core, and U-shaped sheets of magnetic material inserted between thesuperimposed non parallel sides of the trapezoidal sheets in such a wayas to embrace the notches between the adjacent non-parallel sides of thev trapezoidal sheets of each layer.

7. An apparatus of the class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material, each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezodial shape with thetops of said trapezoids adjacent each other, whereby notches are formedbetween the adjacent non-parallel sides of the trapezoidal sheets ofeach layer, the sheets of every alternate layer being arranged at aright angle to the sheets of every other layer, registering notches inthe top of each trapezoidal sheet whereby a central opening is formed inthe core. coils adapted to carry a controlling current located insaidnotches and 'U-shaped sheets of magnetic material inserted between thesuperimposed non-parallel sides of the trapezoidal sheets in such a wayas to embrace the notches between the adjacent nonparallel sides of thetrapezoidal sheets of each layer, whereby magnetic circuits arecompleted for fluxes produced by controlling current in said coils.

8. An apparatus of the class described comprising a magnetic core madeup of a plurality of layers of magnetic material separated by sheets ofinsulating material, each layer of magnetic material being made up oftwo similar sheets of magnetic material of trapezoidal shape with thetops of said trapezoids adjacent each other, whereby notches are formedbetween the adjacent non-parallel sides of the trapezoidal sheets ofeach layer, the sheets of every. alternate layer being arranged at aright angle to the sheets of every other layer, registering notches inthe top of each trapezoidal sheet whereby a central opening is formed inthe core, coils adapted to carry high frequency current located in saidcentral opening and said notches'so as to inclose portions of themagnetic core, coils adapted tocarry a controlling current located insaid natches and U-shaped sheets of magnetic material inserted betweenthe superimposed non-parallel sides of the trapezoidal sheets in such away as to embrace the notches between the adjacent non-parallel sides ofthe trapezoidal sheets of each layer, whereby magnetic circuits arecompleted for fluxes produced by controlling current in said coils.

9. An apparatus of the class described comprising a magnetic core, aplurality of separate windings on said core adapted to.

carry high frequency current and a plurality of separate windings onsaid core adapted to carry a controlling current, the core being soconstructed and the windings being so disposed thereon as to provide asingle magnetic circuit for the fluxes produced by all of the highfrequency windings and a plurality of magnetic circuits tor the fluxesproduced by the controlling windings, the controlling windings being innon-inductive relation to the high frequency windings and each of themagnetic circuits for the controlling fluxes including a portion of themagnetic circuit for the high frequency flux.

10.'An apparatus of the class described comprising a magnetic core madeup of a plurality of thin sheets of magnetic material separated bysheets of insulating material.

the area of the sheets of'insulating material being greater than thearea of the sheets of magnetic material so that their edges project 7beyond those of the sheets of magnetic madi'nary radio frequencies, aset of windings arranged on said core and adapted to carry a highfrequency current and a second set of windings on said core adapted tocarry a controlling current.

1L An apparatus of the class described comprising a magnetic core madeup of a plurality of thin sheets of magnetic n-iaterial separated bysheets of insulating material, thearea of the sheets of insulatingmaterial being greater than the area of the sheets of magnetic material,so that their edges project beyond those of the sheets ofmagneticmaterial, the magnetic material being of 'such a nature and insuch thin sheets that its permeability is substantially independent ofthe frequency of the magnetizing current at ordinary radio frequencies,a set of windings arranged on said core and adapted to carrya highfrequency current and a second set of windings on said core adapted tocarry a controlling current, the two sets of windings being innon-inductive relation to each other.

12. An apparatus of the class described comprising a magnetic core madeup of a plurality, of thin sheets of magnetiomaterial separated bysheets of insulating material, the area of the sheets of insulatingmaterial being greater than the area of the sheets of magnetic materialso that their edges project beyond those of the sheets of magneticmaterial, the sheets of magnetic material being so arranged that certainportions of the core have a 'smuch smaller cross sectional area thanother portions, the magnetic material being of such a nature and insuchthin sheets that its permeability is substantially independent of thefrequency of the magnetizing current at ordinary radio frequencies, aset of windings arranged on said'co're and adapted to carry a highfrequency current and a second set of windings on said core adapted tocarry a controlling current.

13. An apparatus of the class described comprising a magnetic core, aplurality of separate windings on said core adapted to carry highfrequency current and a plurality of separate windings on said coreadapted to carry a controlling current, the core being so constructedand the windings being so disposed thereon as to provide a singlemagnetic circuit for the fluxes produced by all of the high frequencywindings and a plurality of magnetic circuits for the fluxes produced bythe controlling windings, the controlling windings being innon-inductive relation to the high frequency windings and each of the ma'netic*circuits for the controlling fluxes mcluding a portion of themagnetic circuit for the high frequency flux, the controlling magneticcircuits being made up in part of removable yokes whereby thecontrolling windings may be removed independently of the high frequencywindmgs.

14. An apparatus of the class described comprising a magnetic core, aplurality of separate windings on said core adapted to carry a highfrequency current, and a plu cross sectional area than other portionsand each of the magnetic circuits for the controlling fluxes includingone of the portions of the magnetic circuit for the high frequency fluxof relatively small cross section.

15. An apparatus of the class described comprising a magnetic core, aplurality of separate windings on said core adapted to carry a highfrequency current, and a plu rality of separate windings on said coreadapted to carry a controlling current, the core being so constructedand the windings being so disposed thereon as to provide a singlemagnetic circuit for the fluxes produced by all of the high frequencywindings and a plurality of magnetic circuits for the fluxes producedby'the controlling winding which are entirely independent of oneanother, the magnetic circuit for the high frequency flux havinga'plurality of portions of smaller cross sectional area than otherportions and each of the magnetic circuits for the controlling fluxesincluding one of the portions of the magnetic circuit for the highfrequency flux of relatively small cross section.

16. An apparatus of the class described comprising a magnetic core, apluralitv of I separate windings on said core adapted to carry a highfrequency current, and a plu rality of separate windings on said coreadapted to carry a controlling current, the core being so constructedand the windings being so disposed thereon as to provide a singlemagnetic circuit for the fluxes produced by all of the high frequencywindings and a plurality of magnetic circuits for the 'ings and aplurality of magnetic circuitsfor the fluXes produced by the controllingWindings, the controlling windings being in noninductive relation to thehigh frequency 10 windings andeztch of'the magnetic circults for thecontrolling fluxes being partly coincident with and partly separate fromthe magnetic circuit for the high frequency flux.

In Witness whereof, I have hereunto set 15 my hand this 10th day ofApril, 1918.

' ERNST F. W. ALEXANDERSON.

